The present invention relates to an apparatus for error correction in precision machines and measuring instruments, particularly in length-measuring instruments in which a scale is fastened to a carrier for measuring the relative position of two objects.
Several types of apparatus and methods for the correction of machine and scale errors are known to those skilled in the art. For example, German Pat. No. 866,402 discloses a measuring apparatus having a correction rule in which the measurement cursor is controlled mechanically into a position corresponding to the respective error of a spindle with respect to the scale. U.S. Pat. No. 3,039,032 discloses a position measuring system including a correction template which is scanned by a sensor that acts directly on the measurement indicator. Yet another error correction system is described in German Patent specification OS 2,042,505, in which a numerical measuring system of a machine is adjusted by an additional movement corresponding to the respective error value of the machine spindle through a tracking member which scans a correction template. Each of the foregoing correction arrangements utilizes a separate correction template or correction rule, which is fastened to the measuring instrument and adjusted in place after the measuring instrument is produced.